To come or not to come, that is the question..

[Robertburton]

I get where your coming from but i wouldnt be always able to afford hour long punts to be honest.

I would suggest saving up for an hour long one. If you pay for 2 30 min appointments and you're out in 15 mins in each, then you're essentially losing out on a full 30 min appointment. Wait until you have the funds for an hour and then do that.
You'll likely get 2 goes in an hour and even if you last 10 mins the first time, you won't be kicked out and have 50 mins of fun left.